Re: input-pending-p after make-frame-visible

[Gregory Heytings <gregory@heytings.org>]

>>> What is "the original frame"?  There is apparently a single (visible) 
>>> frame in the recipe.
>>
>> Yes, but at least on macOS, that frame loses focus after the first C-x 
>> C-x. It's possible that the child frame has focus instead, even though 
>> it is invisible.
>
> Awkward.  Can you try calling 'frame-focus-state' on both frames to find 
> out whether Emacs itself has an idea of which frame has focus?
>

FTR, I can reproduce this on macOS, with Emacs 27.2.  A more detailed 
recipe is:

1. emacs -Q
2. eval-buffer the recipe
3. C-x C-x
4. click on the original frame
5. click on the echo area of the original frame

After step 3 the invisible frame has the focus and the visible frame does 
not have the focus.  For example, C-x b makes the invisible 
"mini-frame-frame" frame visible again.

Steps 3 and 4 can be repeated, they will always return input-pending-p 
{before,after} = nil.

After step 5, which creates a window with the *Messages* buffer, steps 3 
and 4 can be repeated again, they will always return input-pending-p 
before = nil, input-pending-p after = t.  This is not 100% reproductibe 
however, it's what happens most of the times.